Experimental evidence indicates that the offspring of dams fed the junk-food diet during gestation and lactation developed higher rates of obesity, greater elevations in glucose and insulin levels and had an increased risk of fatty liver disease, as well as signs of steatosis and liver damage, when given free access to the same junk-food diet, compared with rats whose mothers had received a normal chow diet. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.